Semiconductors have been widely used in e.g., electronic equipment, communication machines and personal computers. Recently high integration, high function and dense package of the semiconductors have been more and more accelerated. According to the tendency, requirements for laminates used in semiconductor packages have been diversified. In addition to the properties such as heat resistance, chemical resistance, flame retardation and reliability conventionally required, various properties including low thermal expansion, high glass transition temperature and high elasticity are required.
In recent years, in particular, a laminate with low thermal expansion has been strongly required. This is because the coefficient of thermal expansion between semiconductor devices and a printed-wiring board for a semiconductor plastic package is conventionally large, and thus, if thermal shock or the like is applied in manufacturing steps, the semiconductor plastic package warps due to the thermal-expansion difference between them, with the result that connection failure occurs between semiconductor devices and the printed-wiring board for a semiconductor plastic package and between a semiconductor plastic package and the printed-wiring board to be packaged.
As a method for reducing the coefficient of thermal expansion along the plane of a laminate, using an inorganic filler is a conceivable approach. It was difficult to blend an inorganic filler in a large amount, however, because it is necessary to blend a multifunctional resin to maintain a high glass transition temperature and the multifunctional resin is highly viscous. As another approach, it is known to add an organic filler having rubber elasticity to a varnish containing an epoxy resin (Patent Documents 1 to 6). As another approach for obtaining the same effect as in adding a rubber elastic component while maintaining a charge amount of inorganic filler, blending a silicone resin is known (Patent Documents 7 to 9).